1. Field of the Invention
The present invention relates to an image display apparatus, and more particularly, to an image display apparatus comprising a temperature-equalizing device for equalizing a temperature of a panel. The present application is based on Korean Patent Application No. 2002-0002432, filed Jan. 16, 2002, which is incorporated in full by reference herein.
2. Description of the Prior Art
A plasma display panel (PDP) is a panel made of two base plates of glass which are fixed to each other in an air-tight manner. The PDP displays an image by utilizing a gas discharge phenomenon and requires a relatively simple fabrication process. Using a PDP, it is also easy to make a large and thin display screen. The PDP emits a large amount of heat during the operation due to the gas discharge phenomenon. Most of the PDPs have a radiating apparatus that uses a fan and is disposed at a rear end of the panel, for releasing the heat outwardly.
FIG. 1 is a cross sectional view showing an interior of a PDP having a conventional radiating apparatus.
Referring FIG. 1, a PDP 100 having a conventional radiating apparatus comprises a filter 110, a panel 120, a radiating plate 130, a radiating fan 140, a front casing 150 and a rear casing 160. The filter 110 protects an image display apparatus such as the panel 120 from an external shock. The filter 110 mainly uses glass. The panel 120 consists of two base plates of glass formed typically with a gap of approximately 0.1 mm therebetween. The gap between the two base plates is under vacuum, and there occurs a gas discharge phenomenon in the gap. Accordingly, the PDP 100 displays an image by utilizing the gas discharge phenomenon that occurs in the vacuous gap.
On a rear surface of the panel 120 is provided the radiating plate 130 for equalizing a temperature of the panel 120. The radiating plate 130 uses metallic plate of a high thermal conductivity such as aluminum. At a rear surface of the radiating plate 130 is provided at least one radiating fan 140 for cooling the panel 120 during the operation of the PDP 100.
That is, when the PDP 100 is driven, heat is generated inside the panel 120 due to the gas discharge phenomenon. Most of the generated heat is conducted to the radiating plate 130 disposed at the rear surface of the panel 120. The radiating fan 140 circulates inner air of the PDP 100 to cool the radiating plate 130. When the PDP 100 does not include the radiating fan 140, the radiating plate 130 is cooled by a natural convection caused by a temperature difference.
FIG. 1 shows the front casing 150 in a thick solid line and the rear casing 160 in a dotted line. The front casing 150 is disposed at a front surface of the PDP 100 where the filter 110 is disposed and the rear casing 160 is typically disposed at a rear surface of the PDP 100 where the radiating fan 140 is disposed, thereby protecting the PDP 100 from an external shock.
However, power that is consumed for driving the PDP 100 is converted to heat and discharged outwardly. The heat emitted from the PDP 100 heats the PDP 100 and ambient air of the PDP 100, causing a convection phenomenon. A boundary layer is formed around the PDP 100 due to the convection phenomenon. The boundary layer typically needs to be made gradually thicker towards its upper end, and the upper end of the boundary layer has a higher temperature during operation of the PDP 100 than a lower end of the boundary layer. Another main reason that the upper end has a higher temperature than the lower end is that an exhaust operation is not smoothly performed due to the presence of the rear casing 160.
FIG. 2 is an isothermal line showing a temperature distribution of the panel when the PDP is driven.
Referring to FIG. 2, the temperature distribution is irregular when the PDP 100 is driven and there is a great temperature difference between the upper end and the lower end. The temperature difference increases as the panel 120 is enlarged in size.
The temperature difference of the panel 120 shortens a life span of the PDP 100, and the upper end and the lower end have different capacities such that an even quality of image cannot be obtained. With a larger size PDP 100 especially, the temperature difference between the upper end and the lower end of the panel 120 increases. Also, there is a limit on the ability to equalize the temperature of the panel 120 with the radiating plate 130 and the radiating fan 140. Also, since the PDP 100 comprises the radiating fan 140 for cooling the PDP 100, it is difficult to make the PDP 100 thinner. Additionally, power consumption is increased, and there is a problem of noise.
The present invention has been developed in order to solve the above problems in the prior art. Accordingly, an object of the present invention is to provide an image display apparatus comprising a temperature-equalizing device for equalizing a temperature of a panel.
The object is achieved by providing an image display apparatus comprising: an image display unit for displaying an image on a screen; and a radiating plate having a heat transmission unit for equalizing a surface temperature of the image display unit by circulating heat emitted from the image display unit.
More specifically, the heat transmission unit is a loop heat pipe, and the loop heat pipe has a small amount of operation fluid injected into an inside thereof, the inside of the loop heat pipe being under vacuum. The heat transmission unit is shaped in a closed loop and is disposed around an edge of the radiating plate. The heat transmission unit is shaped in a closed loop and is formed in a zigzag fashion.
According to the present invention, the image display apparatus is provided with the loop heat pipe, such that the temperature of the panel is equalized. Accordingly, the life span of the image display apparatus can be extended, and the equalized temperature of the panel can reduce a brightness difference that is caused by the temperature difference.